U.S. patent number 10,583,605 [Application Number 15/957,050] was granted by the patent office on 2020-03-10 for drop draw/extrude (dd/e) printing method.
This patent grant is currently assigned to THE BOEING COMPANY. The grantee listed for this patent is The Boeing Company. Invention is credited to Michelle Louise Gee, Justin Hicks, Christopher A. Howe, Adrian Mouritz, Thomas Wilson.
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United States Patent |
10,583,605 |
Howe , et al. |
March 10, 2020 |
Drop draw/extrude (DD/E) printing method
Abstract
A drop draw and extrusion method that creates anchor points
around, within, or around and within, the region where a two
dimensional fibrous architecture is deposited. Between the anchor
points, a nozzle translates at high speeds to draw, extrude, or
draw and extrude (depending on the print settings), a filament from
the nozzle and build a two dimensional network of filaments
connected by the anchors. Webbed architectures fabricated using the
methods described herein exhibit superior structural
properties.
Inventors: |
Howe; Christopher A. (Port
Melbourne, AU), Hicks; Justin (Noorat, AU),
Gee; Michelle Louise (Bundoora, AU), Wilson;
Thomas (Port Melbourne, AU), Mouritz; Adrian
(Melbourne, AU) |
Applicant: |
Name |
City |
State |
Country |
Type |
The Boeing Company |
Chicago |
IL |
US |
|
|
Assignee: |
THE BOEING COMPANY (Chicago,
IL)
|
Family
ID: |
66102890 |
Appl.
No.: |
15/957,050 |
Filed: |
April 19, 2018 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
|
US 20190322037 A1 |
Oct 24, 2019 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B05D
7/00 (20130101); B05D 1/40 (20130101); B33Y
10/00 (20141201); B29C 64/393 (20170801); B29C
64/20 (20170801); B05D 1/42 (20130101); B29C
64/118 (20170801); B29C 64/209 (20170801); B29C
64/106 (20170801); B29C 64/232 (20170801); B33Y
50/02 (20141201); B33Y 30/00 (20141201); B29K
2101/12 (20130101); B33Y 70/00 (20141201) |
Current International
Class: |
B29C
64/118 (20170101); B33Y 30/00 (20150101); B29C
64/393 (20170101); B33Y 50/02 (20150101); B29C
64/106 (20170101); B29C 64/209 (20170101); B33Y
10/00 (20150101); B05D 7/00 (20060101); B29C
64/20 (20170101); B05D 1/42 (20060101); B05D
1/40 (20060101); B33Y 70/00 (20200101) |
Field of
Search: |
;264/103,210.8,211.15,203,211.14 ;425/66,72.2,461 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3000922 |
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Mar 2016 |
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EP |
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2017100783 |
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Jun 2017 |
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WO |
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Other References
Quick Reference: 7 Families of Additive Manufacturing, copyright
2015-2018 by Hybrid Manufacturing Technologies, retrieved from
http://www.hybridmanutech.com/uploads/2/3/6/9/23690678/7_families_of_3d_p-
rinting_by_hybrid_v11_2p.pdf on Jul. 7, 2019, 2 pages. (Year:
2015). cited by examiner .
Nguyen, A.T.T., et al., "Hierarchical surface features for improved
bonding and fracture toughness of metal-metal and metal-composite
bonded joints", International Journal of Adhesion & Adhesives,
2016, pp. 81-92, vol. 66. cited by applicant .
Vaidya, U.K., et al., "Affordable Processing and Characterization
of Multi-Functional Z-Pin Reinforced VARTM Composites", Proceedings
of the 13th International Conference on Composite Materials, 2001,
pp. 1-10. cited by applicant .
Heimbs, S., et al., "Failure behaviour of composite T-joints with
novel metallic arrow-pin reinforcement", Composite Structures,
2014, pp. 16-28, vol. 110. cited by applicant .
Extended European Search Report dated Sep. 9, 2019 for European
Patent Application No. 19170124.2. cited by applicant .
Extended European Search Report dated Oct. 4, 2019 for European
Patent Application No. 19167994.3. cited by applicant .
Qin, Z., et al., "Structural optimization of 3D-printed synthetic
spider webs for high strength", Nature Communications, May 2015,
pp. 1-7, vol. 6. cited by applicant .
Extended European Search Report dated Oct. 7, 2019 for European
Patent Application No. 19170386.7. cited by applicant .
PCT International Search Report and Written Opinion dated Oct. 7,
2019 for PCT Application No. PCT/US2019/026542. cited by
applicant.
|
Primary Examiner: Fletcher, III; William P
Attorney, Agent or Firm: Gates & Cooper LLP
Claims
What is claimed is:
1. A method for manufacturing a structure, comprising: forming a
plurality of anchors comprising a first anchor and a second anchor,
including: (a) depositing material from a print head, creating the
first anchor at a first position on a substrate; (b) depositing the
material from the print head, creating thia second anchor at a
second position on the substrate and laterally separated from the
first position; and (c) drawing a filament of the material
extending from the first anchor to the second anchor, comprising
creating vertical space between the substrate and the print head,
laterally moving the print head or the substrate or both the print
head and the substrate relative to one another so as to position
the print head above the second position, and moving the substrate
and the print head towards one another so as to connect the
filament to the second anchor; and (d) repeating steps (a)-(c) so
as to construct a pattern of the filaments connecting the plurality
of the anchors.
2. The method of claim 1, wherein the creating of the anchors
and/or the drawing comprises: feeding material for the anchors and
the filaments from a nozzle; and controlling the nozzle's
temperature, a speed of the nozzle relative to the substrate, the
nozzle's height, and a flow rate of the material from the nozzle so
as to fabricate the filaments having different properties at
different two dimensional positions above the substrate, including
different tensile strengths.
3. The method of claim 1, wherein the creating of the anchors
and/or the drawing comprises: feeding material for the anchors and
the filaments from a nozzle; and moving the nozzle or the
substrate, or both the substrate and the nozzle relative to one
another and controlling a flow rate of the material so as to form
the anchors having a minimum diameter in a range of 0.25
millimeters (mm) to 2.0-mm.
4. The method of claim 1, wherein the creating of the anchors
and/or the drawing comprises: feeding material for the anchors and
the filaments from a nozzle; and moving the nozzle or the
substrate, or both the substrate and the nozzle relative to one
another, controlling a flow rate of the material in a range of
0.045-0.5 grams/minute (g/m), controlling a speed of the nozzle
relative to the substrate in a range of 1 to 310 mm/second, and
controlling a height of the nozzle above the substrate in a range
of 0.2-5 mm, so as to form the filaments having a diameter in a
range of 30-450 micrometers.
5. The method of claim 4, wherein the filaments have a filament
diameter in a range between 80-200 microns.
6. The method of claim 4, further comprising positioning the nozzle
at a height in a range of 2-5 mm above the substrate so as to form
the filaments having a filament diameter in a range of 1.5-62% of a
minimum diameter of the anchors.
7. The method of claim 6, wherein the filament diameter is in a
range of 1.5-35% of the minimum diameter of the anchors.
8. The method of claim 4, wherein the drawing comprises moving the
nozzle at a speed relative to the substrate in a range of 50 to 300
mm/seconds.
9. The method of claim 1, further comprising: feeding the material
for the anchors and the filaments from a nozzle; and positioning
the nozzle at a height in a range of 2 to 5 mm above the substrate
so as to draw the filaments having a filament diameter in a range
of 7-100% of the nozzle's diameter.
10. The method of claim 9, wherein the nozzle's diameter is in a
range from 0.2-0.5-mm.
11. The method of claim 1, wherein: the creating of the anchors
comprises feeding the material for the anchors and the filaments
from a nozzle; and the drawing comprises laterally moving the
nozzle or the substrate, or both the substrate and the nozzle
relative to one another at a height in a range from 2 to 5-mm above
the substrate, and a height of the nozzle during the creating of
the anchors is in a range of 0.1 mm-0.4 mm.
12. The method of claim 11, wherein the height is in a range of 4
to 5 mm while drawing the filaments laterally and the height of the
nozzle during creation of the anchors is in a range of 0.2 mm-0.4
mm.
13. The method of claim 1, wherein the creating of the anchors
comprises feeding the material comprising a thermoplastic from the
nozzle and drawing the filament using the nozzle at a temperature
30 to 70.degree. C. above a melting point of the thermoplastic.
14. The method of claim 13, wherein the temperature is 30 to
50.degree. C. above the melting point.
15. The method of claim 1, wherein the creating of the anchors
comprises feeding material for the anchors and the filaments from a
nozzle at a flow rate in a range of 0.045-0.5 grams/minute
(g/m).
16. The method of claim 15, wherein the flow rate is in a range of
0.045 g/min to 0.1 g/min.
17. The method of claim 1, wherein the creating of the anchors
comprises: feeding the material for the anchors and the filaments
from a nozzle; and moving the nozzle or the substrate, or both the
substrate and the nozzle relative to each other, controlling a
speed of the nozzle relative to the substrate, controlling the
nozzle's temperature, and controlling a flow rate of the material
from the nozzle, so as to fabricate the pattern comprising the
filaments disposed in a web.
18. The method of claim 1, wherein the pattern includes a two
dimensional network of the filaments, the two dimensional network
having a maximum length in a range of 5 cm to 10 meters.
19. The method of claim 18, further comprising positioning the two
dimensional network as an adhesive or a mechanical interlocking
device.
20. The method of claim 18, further comprising positioning the two
dimensional network as a thermoplastic veil reinforcing a
composite, wherein the filaments comprise a thermoplastic.
Description
BACKGROUND
1. Field
The present disclosure describes novel additive manufacturing
methods and structures fabricated using the same.
2. Description of the Related Art
Additive Manufacturing (AM) is a process by which three dimensional
parts are made one layer at a time. In a typical example, an AM
machine deposits material in molten form onto a build platform. The
material is solidified on the build platform to form a layer of the
part. Once a single layer of the part has been completed, the AM
machine or build plate moves away in one layer increments and the
AM machine proceeds to deposit the next layer of material. A common
type of AM process is known as Fused Deposition Modeling (FDM), an
extrusion-based process that feeds thermoplastic in solid wire form
from a nozzle and then melts the wire into a shape that is then
re-solidified. However, the FDM process has several limitations
including (1) slower manufacturing times because the nozzle is in
close proximity to the substrate and the thermoplastic needs time
to bond, (2) the diameter of the extruded filament being larger
than is desirable for some applications (3) inability to control
the physical properties of the filament with sufficient precision,
and (4) requiring the use of flat substrates because the close
proximity of the nozzle to the substrate may cause collisions with
non-flat substrates. As a result, conventional FDM is not capable
of fabricating more complex AM structures having specially tailored
properties.
What is needed, then, is an additive manufacturing technique that
can rapidly fabricate a wider range of structures having tailored
properties (e.g., where the properties are locally tailored in two
dimensions). The present disclosure satisfies this need.
SUMMARY
The present disclosure describes a method for manufacturing a
structure, comprising: (a) depositing material (124) from a print
head (102) so as to create a first anchor (116a) at a first
position (116b) on a substrate; (b) depositing the material (124)
from the print head (102) so as to create a second anchor (116c) at
a second position (116d) on the substrate and laterally separated
from the first position (116b); (c) drawing a filament (600) of the
material (124) extending from the first anchor (116a) to the second
anchor (116c), comprising creating a vertical space between the
substrate (112) and the print head (102), laterally moving the
print head (102) or the substrate (112) or the print head (102) and
the substrate (112) relative to one another so as to position the
print head (102) above the second position (116d), and moving the
substrate (112) and the print head (102) towards one another so as
to connect the filament (600) to the second anchor (116c); and (d)
repeating steps (a)-(c) so as to construct a pattern of the
filaments (600) connecting a plurality of the anchors (114a,
114c).
Examples of print conditions during creation of the anchors and/or
drawing of the filaments include, but are not limited to, the
following.
1. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and controlling the nozzle's
(108) temperature, the speed of the nozzle (108) relative to the
substrate (112), the nozzle's height above the substrate (1120, and
a flow rate of the material (124) from the nozzle (108) so as to
fabricate the filaments (600) having different properties at
different two dimensional positions (114b, 114d) above the
substrate (112), including different tensile strengths.
2. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and moving the nozzle (108) or
the substrate (112) or both the nozzle (108) and the substrate
(112) relative to one another and controlling a flow rate of the
material (124) so as to form the anchors (114a, 114b) having a
minimum diameter in a range of 0.25-mm to 2.0-mm. In one or more
examples, the filament diameter is in a range of 1.5-35% of the
minimum diameter of the anchors (114a, 114b).
3. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and moving the nozzle (108) or
the substrate (112) or both the nozzle (108) and the substrate
(112) relative to one another, controlling a flow rate of the
material (124) in a range of 0.045-0.5 grams/minute (g/m),
controlling a speed of the nozzle (108) relative to the substrate
(112) in a range of 1 to 310 mm/second, controlling a height of the
nozzle (108) above the substrate (112) in a range of 0.2-5
millimeters (mm), so as to form the filaments (600) having a
diameter in the range of 30-450 micrometers. In one or more further
examples, the filaments (600) have a filament diameter in a range
between 80-200 microns.
4. Positioning the nozzle (108) at a height in a range of 2-5 mm
above the substrate (112) so as to form the filaments (600) having
a filament diameter in a range of 1.5-62% of a minimum diameter of
the anchors (114a, 114b).
5. Moving the nozzle (108) at a speed relative to the substrate
(112) in a range of 50 to 300 mm/seconds.
6. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and positioning the nozzle
(108) at a height in a range of 2 to 5 mm above the substrate (112)
so as to draw the filaments (600) having a filament diameter in a
range of 7-100% of the nozzle (108)'s diameter. In one or more
examples, the nozzle's diameter is in a range from 0.2-0.5-mm.
7. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and laterally moving the
nozzle (108) or the substrate (112) or both the nozzle (108) and
the substrate (112) relative to one another at a height in a range
from 2 to 5-mm above the substrate (112). In one or more examples,
the height of the nozzle (108) during creation of the anchors
(114a, 114b) is in a range of 0.1 mm-0.4 mm. In one or more further
examples, the height is in a range of 4 to 5 mm while drawing the
filaments (600) laterally and the height of the nozzle (108) during
creation of the anchors (114a, 114b) is in a range of 0.2 mm-0.4
mm.
8. Feeding a thermoplastic from the nozzle (108) and drawing the
filament (600) using the nozzle (108) at a temperature 30 to
70.degree. C. above a melting point of the thermoplastic. In one or
more examples, the temperature is 30 to 50.degree. C. above the
melting point.
9. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108) at a flow rate in a range of
0.045-0.5 grams/minute (g/m). In one or more examples, the flow
rate is in a range of 0.045 g/min to 0.1 g/min.
10. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and moving the nozzle (108) or
the substrate (112) or both the nozzle (108) and the substrate
(112) relative to each other, controlling a speed of the nozzle
(108) relative to the substrate (112), controlling the nozzle's
(108) temperature, and controlling a flow rate of the material
(124) from the nozzle (108), so as to fabricate the pattern
comprising the filaments (600) disposed in a web.
The present disclosure further describes a structure (700),
comprising a plurality of anchors (114a, 114b) on a substrate
(112); and a two dimensional network (702) of interconnected
filaments (600) comprising a material (124) drawn between the
anchors (114a, 114b), wherein the anchors (114a, 114b) have a
minimum diameter in a range of 0.25-mm to 2.0-mm, the filaments
(600) have a diameter in the range of 30-400 micrometers, the
filaments (600) have a height in a range from 2 to 5-mm above the
substrate (112), and the two dimensional network (702) has a
maximum length in a range of 5 cm to 10 meters.
In one or more examples, the two dimensional network (702) is an
adhesive or mechanical interlocking device, or a (e.g.,
thermoplastic) veil (700b) for reinforcing a composite. In one or
more examples, the interconnected network (702) comprises a web
(800) including a plurality of the filaments (600) disposed so as
to form nested rings (802) and a plurality of the filaments (600)
disposed so as to radially connect the nested rings (802).
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings in which like reference numbers
represent corresponding parts throughout.
FIGS. 1A and 1B illustrate exemplary DD/E printers used to
manufacture the composite articles described herein.
FIG. 2A is a flowchart illustrating a method of fabricating
structures using a DD/E technique.
FIG. 2B illustrates the Drop & Draw/Extrude (DDE) 3D printing
process, where (I) an anchor is laid on the substrate, (II) the
head and build platform separate in a vertical movement creating a
gap between the nozzle and the substrate, (III) the head translates
at high speed, dragging a thin strand of thermoplastic with it, to
a position above the next anchor point and, (IV) in another
vertical movement, the nozzle returns to the substrate, (V) and
then deposits the next anchor, where the process begins again.
FIG. 2C illustrates three dimensional (3D) printing in a box
according to one or more examples.
FIG. 2D illustrates large scale 3D printing according to one or
more examples.
FIG. 3 illustrates variations in tensile strength of printed
thermoplastic filaments over a range of print settings using an
exemplary DD/E method.
FIG. 4 illustrates variations in engineering strain of printed
thermoplastic filaments over a range of print settings using an
exemplary DD/E printing method.
FIG. 5 illustrates storage modulus of filaments as a function of
nozzle temperature, using a dynamic mechanical analysis standard
test method per ASTM E1640, with the plotted results calculated
based on the difference between the storage and loss modulus as a
function of temperature. The peak in the tan delta as plotted is
identified to be an indication of the glass transition temperature
for the tested material system.
FIG. 6A illustrates filament diameter as a function of print speed
using the DD/E method.
FIG. 6B illustrates filament diameter as a function of actual
translation speed of the nozzle using the DD/E method, as a
function of filament feed rate in revolutions per minute (RPM),
showing measured data (experimental) as well as results for a model
of the experimental results (model).
FIGS. 6C-6E illustrate control of the filament diameter using the
DD/E method, wherein FIGS. 6C and 6D are different magnification
scanning electron microscope images of the filaments fabricated
according to one or more embodiments, and FIG. 6E is an optical
image of the filaments fabricated according to one or more methods
described herein.
FIG. 6F illustrates how the DD/E method controls direction of the
filaments, spacing of the filaments, and filament diameter, and
aerial weight as a function of position in the x-y plane. FIG. 6F
shows manufacturing of three designs, 3 fiber diameters, and 9
variations in areal weight.
FIGS. 7A-7C illustrate a veil interlaminar architecture printed
using the DD/E method, showing controlled filament diameters,
controlled direction and location of filaments, wherein FIG. 7B is
a close up view showing the anchor points around the edge and FIG.
7C shows the region that results from the DD/E process when there
is space between the nozzle and the substrate.
FIG. 8A-8D illustrate webbed architecture fabricated using the DD/E
method, wherein FIG. 8B is a close up of FIG. 8A, FIG. 8C is a
close up view showing the joint between radially disposed filaments
and the filaments disposed in rings.
FIGS. 9A-9D illustrates the performance under a 270 in-lb impact of
a composite including a webbed veil described herein, as compared
to a conventional veil having the structure illustrated in FIG. 9E,
wherein FIGS. 9A and 9B show the impact on the composite an
additively manufactured nylon web veil fabricated according to
embodiments of the present invention, and FIGS. 9B and 9D show the
impact on the composite without the webbed veil but having a
non-woven fabric veil as illustrated in FIG. 9E).
FIG. 10 illustrates target properties achievable using the webbed
design described herein.
FIG. 11 is an example computer hardware environment for controlling
the DD/E machine according to embodiments of the present
disclosure.
DESCRIPTION
In the following description, reference is made to the accompanying
drawings which form a part hereof, and which is shown, by way of
illustration, several embodiments. It is understood that other
embodiments may be utilized and structural changes may be made
without departing from the scope of the present disclosure.
Technical Description
The present disclosure describes an additive manufacturing
technique, termed drop-draw extrusion (DD/E), enabling greater
control of additively deposited filaments that are drawn and/or
extruded from an additive manufacturing (AM) machine.
FIGS. 1A and 1B illustrate an exemplary additive deposition machine
100 comprising a print head 102, extruder 104, feeder 106, and
nozzle 108 for feeding material (e.g., a filament 110) onto a
substrate 112 on a build platform or printer bed 114. In one or
more examples, the machine 100 is a desktop Fused Deposition
Modeling (FDM) 3D printer. FIG. 1A further illustrates the anchor
points or anchors 116a, 116c deposited on the substrate 112 around,
within, or around and within, the region where a two dimensional
fibrous architecture is to be deposited.
The machine 100 can drag and draw a filament of the material (124)
extending from the first anchor 116a at a first position 116b on
the substrate 112 to the second anchor 116c at a second position
116d on the substrate 112, by creating a vertical space 118 between
the substrate 112 and the print head 102 above the first position
116b of the first anchor 114a, laterally moving (in an x-y plane
120) the print head 102 or the substrate (112), or both the print
head (102) and the substrate 112 relative to one another so as to
position the print head 102 above the second position 116d and drag
and draw the filament between the first position 116b and the
second position 116d, and moving the substrate 112 and the print
head 102 towards one another in the vertical direction 122 so as to
connect the filament to the second anchor 116c. Material (124) may
be dragged across from one anchor point to another repeatedly to
make a pattern of material (124) and the vertical space and lateral
translation can be achieved by moving the nozzle (108) and/or the
print bed (114).
In one or more examples, the anchor (116a, 116b) is defined as a
substrate, foundation, and/or source for the filament (600, 110)
providing the material (124) for the filament (600, 110) and/or
providing something for the filament (600,110) to stick to once the
filament (600) is formed.
FIG. 2A is a flowchart illustrating the process of additively
manufacturing a structure on a substrate 112, e.g., using the AM
machine illustrated in FIGS. 1A and 1B. Anchor points may be
created before or after the connection of the anchor points with
filaments (600). Example substrates include, but are not limited
to, fibrous substrates comprising fiber tows fabricated from at
least one material (124) chosen from fiberglass, kevlar, and
carbon. In one or more examples, the fiber tows are woven, e.g., so
as to form a fiber mat. In other embodiments, the substrate
comprises unidirectional tape with regular slits (comprising
parallel tows with gaps therebetween), braids (e.g., stitched
fabrics), or multi-axial reinforcements.
Block 200 represents creating (e.g., printing) an anchor (e.g.,
first anchor (116a) or anchor point) on a surface of a substrate
112. In one or more examples, the anchor (116a, 116b) is defined as
a substrate, foundation, and/or source for the filament (600, 110)
providing the material (124) for the filament (600, 110) and/or
providing something for the filament (600,110) to stick to once the
filament (600) is formed. In one or more examples, material (124)
is deposited from an outlet (e.g., nozzle 108)) onto the substrate
using the machine illustrated in FIG. 1 or FIG. 2B(I). Examples of
the material (124) include at least one material (124) chosen from
a polymer (e.g., nylon, polyetherketoneketone (PEKK),
polyaryletherketone (PEK), polyimide), carbon, a carbon nanotube, a
clay modifier, a thermoplastic (e.g., thermoplastic polymer), a
hybrid thermoplastic, and metal.
Block 202 represents creating a space between the substrate and the
outlet (e.g., nozzle (108)). In typical examples, either the nozzle
translates upwards or the substrate translates downwards. For
example, after the nozzle (108) deposits an anchor (116a) directly
onto the surface of a substrate, the build platform drops away
(e.g., vertically) from the nozzle (108) (or the nozzle (108)
translates upward or vertically from the substrate) creating a
large space between the substrate and the nozzle (108) while
extruding/drawing a filament from the nozzle (108), as illustrated
in FIG. 2B(II). In one or more examples, the nozzle (108) pulls on
a drop of material while also supplying more of the material (124)
to thin the material out into a filament or string.
Block 204 represents laterally and/or vertically (e.g.,
horizontally and/or vertically or simultaneously horizontally and
vertically) moving the outlet (e.g., nozzle 108) or the substrate
(112), or both the outlet and the substrate (112) relative to one
another so as to position the outlet above the second position
(116d) on the substrate. In one or more examples, the step includes
moving the substrate (112) and/or print head (102) so as to)
translate the print head (102) in mid-air (i.e., with vertical
space between the nozzle (108) and the substrate (112)) while
drawing/extruding the filament from the outlet. A string of thin
deposition is created mid air (with vertical space between the
nozzle (108) and the substrate (112)) by this movement, e.g., as
illustrated in FIG. 2B(III). In one or more examples, vertical
movement during translation creates increased space between the
nozzle and the substrate.
Block 206 represents stopping the outlet and/or the substrate (112)
so as to position the outlet at a next location (e.g., second
position 116d) above the substrate (112).
Block 208 represents moving the outlet and/or substrate together
again at the next location/position of the next anchor point (e.g.,
second anchor 116c), e.g., as illustrated in FIG. 2B(IV).
Block 210 represents repeating at least Block 200 to create a
second anchor (116c) point on the substrate at the next location,
e.g., as illustrated in FIG. 2B(V).
Steps 200-210 may be repeated in sequence a plurality of times to
create a plurality of anchor points and laying material from one
anchor to another as the outlet draws or pulls a filament extending
from one anchor to the other. In this way, a two dimensional
structure or architecture comprising the filaments (600) connecting
anchor points is constructed.
The process may control the form and size of architectures in a
single flat/curved plane as opposed to creating a thick "3D"
object. In various examples, the architectures or patterns 700c can
be deposited on a moving "roller" device, or directly onto a
reinforcement.
FIG. 2C shows formation of the thermoplastic architectures on a
flat printer bed in a box (250). However, the DD/E methods
described herein may also be implemented out of the printer box",
for example, using an extruder head attached to a robot end
effector as illustrated in FIG. 2D.
Moreover, control of the process parameters and inputs (nozzle
speed, nozzle position, nozzle temperature, and/or material flow
rate from the nozzle) enables the simultaneous and/or independent
control of diameter of the filaments (600) (can be controlled at a
given location by depositing material according to a power law as
described below). In various examples, diameter of the filaments is
controlled by the nozzle speed relative to the substrate and/or the
amount of material/feed rate). The action of dragging the material
controls the thickness of diameter of the filament (e.g., dragging
the material thins the material). Thin filaments can be strong but
light. In one or more embodiments, the material (e.g.,
thermoplastic) content is minimized by reducing the diameter so as
to reduce weight while keeping a threshold strength. direction of
filaments (600) (controlled by movement of the nozzle in an x-y
plane); location of the filaments (600); material properties of the
filaments (600). In one or more examples, surface morphology of the
filaments is controlled by (speed of the nozzle relative to the
substrate, temperature of the nozzle, moisture content (steam
creates bubbles and roughness on material) and/or position of the
nozzle. variation of fibrous architecture (e.g., throughout the
same interlaminar region) in the same manufacturing step (multiple
architectures in the same step) using the same AM machine. For
example, direction of the filaments (600), spacing of the filaments
(600), and filament diameter, and aerial weight can be varied as a
function of position in the x-y plane.
In one or more embodiments, drawing straight sections of (e.g.,
thermoplastic) filaments (600) between two "anchor points" at high
speed reduces the filament diameter, uses less material, provides
extended control over the thermoplastic material properties on a
localized basis, and increases manufacturing speed.
Examples of print conditions during creation of the anchors and/or
drawing of the filaments include, but are not limited to, the
following.
1. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and controlling the nozzle's
(108) temperature, the speed of the nozzle (108) relative to the
substrate (112), the nozzle's height above the substrate (1120, and
a flow rate of the material (124) from the nozzle (108) so as to
fabricate the filaments (600) having different properties at
different two dimensional positions (114b, 114d) above the
substrate (112), including different tensile strengths.
2. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and moving the nozzle (108) or
the substrate (112), or both the nozzle (108) and the substrate
(112) relative to one another/each other and controlling a flow
rate of the material (124) so as to form the anchors (114a, 114b)
having a minimum diameter in a range of 0.25-mm to 2.0-mm. In one
or more examples, the filament diameter is in a range of 1.5-35% of
the minimum diameter of the anchors (114a, 114b).
3. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and moving the nozzle (108) or
the substrate (112), or both the nozzle (108) and the substrate
(112) relative to one another/each other, controlling a flow rate
of the material (124) in a range of 0.045-0.5 grams/minute (g/m),
controlling a speed of the nozzle (108) relative to the substrate
(112) in a range of 1 to 310 mm/second, controlling a height of the
nozzle (108) above the substrate (112) in a range of 0.2-5 mm, so
as to form the filaments (600) having a diameter in the range of
30-450 micrometers. In one or more further examples, the filaments
(600) have a filament diameter in a range between 80-200
microns.
4. Positioning the nozzle (108) at a height in a range of 2-5 mm
above the substrate (112) so as to form the filaments (600) having
a filament diameter in a range of 1.5-62% of a minimum diameter of
the anchors (114a, 114b).
5. Moving the nozzle (108) at a speed relative to the substrate
(112) in a range of 50 to 300 mm/seconds.
6. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and positioning the nozzle
(108) at a height in a range of 2 to 5 mm above the substrate (112)
so as to draw the filaments (600) having a filament diameter in a
range of 7-100% of the nozzle (108)'s diameter. In one or more
examples, the nozzle's diameter is in a range from 0.2-0.5-mm.
7. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and laterally moving the
nozzle (108) or the substrate (112), or both the nozzle (108) and
the substrate (112) relative to one another/each other at a height
in a range from 2 to 5-mm above the substrate (112). In one or more
examples, the height of the nozzle (108) during creation of the
anchors (114a, 114b) is in a range of 0.1 mm-0.4 mm. In one or more
further examples, the height is in a range of 4 to 5 mm while
drawing the filaments (600) laterally and the height of the nozzle
(108) during creation of the anchors (114a, 114b) is in a range of
0.2 mm-0.4 mm.
8. Feeding the material (124) comprising a thermoplastic from the
nozzle (108) and drawing the filament (600) using the nozzle (108)
at a temperature 30 to 70.degree. C. above a melting point of the
thermoplastic. In one or more examples, the temperature is 30 to
50.degree. C. above the melting point.
9. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108) at a flow rate in a range of
0.045-0.5 grams/minute (g/m). In one or more examples, the flow
rate is in a range of 0.045 g/min to 0.1 g/min.
10. Feeding material (124) for the anchors (114a, 114b) and the
filaments (600) from a nozzle (108); and moving the nozzle (108) or
the substrate (112), or both the nozzle (108) and the substrate
(112) relative to one another/each other, controlling a speed of
the nozzle (108) relative to the substrate (112), controlling the
nozzle's (108) temperature, and controlling a flow rate of the
material (124) from the nozzle (108), so as to fabricate the
pattern comprising the filaments (600) disposed in a web.
Controlling Material Properties
FIGS. 3, 4, and 5 illustrate how additive manufacturing deposition
conditions (nozzle temperature) changes and/or controls the
material properties of the filaments. The variations in the tensile
strength and engineering strain have been included as examples,
however other material properties can also be controlled through
the additive manufacturing process by controlling influential
printer inputs, such as feed rate, thermoplastic flow rate, and
nozzle temperature.
FIG. 6A plots fiber diameter as a function of print speed and
nozzle temperature. The diameter D of the filament (600) was found
to be a function of flow rate (F.sub.rate) of material (124) into
and out of the nozzle (108)), seep or flow rate (m.sub.seep) of
material flowing under gravity from extruder (104) into nozzle, and
time (t.sub.delay) taken moving the nozzle from one point (e.g.,
first position 116b) to another point (e.g., second position 116d)
above the substrate). The power law equation was generated using
empirical data and physics based relationships and relates how to
control the filament diameter as a function of extrusion
temperature, head translation speed (mm/sec), and thermoplastic
flow rate (g/min).
FIGS. 6B-6D are results confirming how thinner filament lines can
be fabricated by having the printer head farther away and/or by
varying the printer head speed. In one or more embodiments, the
printer head speed is the same as the speed of the nozzle (108)
connected to the printer head.
Control of printing parameters assists in producing
high-performance interlayer technologies comprising laminated
composite material with tailored properties for particular system
applications. Conventional assembly techniques can only process at
a single setting for the entire architecture, and therefore cannot
vary material properties on a location by location basis as
provided for by exemplary embodiments described herein. FIG. 6E
illustrates how the DD/E method controls direction of the
filaments, spacing of the filaments, and filament diameter, and
aerial weight as a function of position in the x-y plane (in region
A, the filament diameter is 0.04 mm, in region B the filament
diameter is 0.03 mm).
Example Structures
FIG. 7A illustrates a structure (700) fabricated using the method
illustrated in FIG. 2. The structure (700) comprises a plurality of
anchors (116a, 116c) on a substrate (112); and a two dimensional
network (702) of interconnected filaments (600) comprising a
thermoplastic drawn between the anchors (116a, 116b). Example
dimensions for the anchors include a minimum diameter D2 in a range
of 0.25-mm to 2.0-mm. Example dimensions for the filaments 600
include a diameter D in the range of 30-400 micrometers. Example
lengths L of the filaments include a length in a range of 5 cm to
10 meters (e.g., so that the two dimensional network has a
diameter, width W, or length L in a range of 5 cm to 10
meters).
The structure 700 illustrated in FIGS. 7A-7C is a veil 700b
interlaminar architecture for implementation in a laminated
composite material system (veil toughened composite). In typical
examples, the a toughened composite includes a plurality of
alternating layers alternating between the carbon fiber mat and the
two dimensional structure. As described herein, embodiments of the
DD/E method provide much greater flexibility in design of
architectures for interlayer toughening technologies, including,
but not limited to, control over direction of the filaments,
diameter of filaments, and location of the filament.
The methods described herein also allow for multiple architectures
to exist in the same interlaminar region (e.g., the architecture
can be varied on a location by location basis) in the same
manufacturing step. FIGS. 8A, 8B, 8C, and 8D illustrate an example
where the structure 700 comprises a web 800 including filaments 600
disposed in nested rings 802 as well as radially so as to connect
the rings 802. The location of the radially disposed filaments 804,
the mesh width 806 (see FIG. 8D), the filament diameter D (e.g., in
a range of 7-150 microns), the web radius 808, the areal weight
(e.g., in a range of 1.5-2.5 gsm), surface morphology of the
filaments, may all be varied locally in the two dimensional plane,
as desired. In one or more embodiments, the web is designed to
mimic the performance of a spider's web.
FIGS. 9A-9D illustrate the performance of a toughened composite
wherein the veil layer comprises a web architecture as illustrated
herein. The data shows >30% reduction in length and area of the
impact damage area 900, spherical crack containment, dent depth
under a 270-inlb impact in a range of 0.014 to 0.016-inches, and
compression after impact CAI under a 270-inlb impact of 30 ksi (vs
25 ksi as compared to a control device where the veil layer
comprises randomly disposed fibers as illustrated in FIG. 9E).
FIG. 10 shows that the spider based web structure described herein
performs at least as well as nanofibrous interleaves.
Applications of the two dimensional fibrous architectures are not
limited to veils or a toughening architectures. In other examples,
the two dimensional structure is used as an adhesive or mechanical
interlocking device. In one example, the adhesive comprises one
surface including the two dimensional network of filaments and
another surface including hooks, wherein the surfaces are adhered
when the hooks hook onto the filaments.
Advantages and Improvements
Conventional FDM creates 3D parts by depositing layers of
thermoplastic on top of one-another (layer by layer). However, this
process has the following drawbacks as compared to exemplary drop
draw extrusion methods described herein:
(1) FDM is slow--because the nozzle is in close proximity to the
preceding layer, and the thermoplastic needs time to bond to the
preceding layer, the feed rate (rate at which the nozzle
translates) is slower than achievable using exemplary DD/E
methods.
(2) The diameter of filament that is produced using FDM is larger
than achievable using exemplary DD/E methods. Moreover, the DD/E
method described herein is capable of producing a larger range of
repeatable thermoplastic filament diameters as compared to
conventional FDM.
(3) Conventional FDM is performed on flat substrates to avoid
collision of the nozzle with the substrate which could occur on
curved or non-flat substrates (resulting in failed prints).
Illustrative DD/E methods, on the other hand, are capable of
depositing on non flat (e.g., curved) substrates because the DD/E
process does not deposit material directly on top of a preceding
layer, instead, only anchor points are formed on the substrate and
there is a large space between the substrate and the nozzle while
drawing/extruding the filaments from the nozzle. As a result the
nozzle can translate at much higher speeds without the risk of
collision with the substrate. The larger space between the nozzle
and the substrate also reduces the likelihood of print head
collisions between the substrate and the two dimensional printed
architecture, improving reliability and success rate of the
process.
(4) Large conventional industrial equipment that is run in batches
can only create large areas of a single, non varying, architecture.
Their major drawback is the inability to vary direction, diameter,
form, and physical properties of the architecture on a location by
location basis as can be achieved using exemplary DD/E methods
described herein.
Processing Environment
FIG. 11 illustrates an exemplary system 1100 used to implement
processing elements needed to control the AM machine described
herein.
The computer 1102 comprises a processor 1104 (general purpose
processor 1104A and special purpose processor 1104B) and a memory,
such as random access memory (RAM) 1106. Generally, the computer
1102 operates under control of an operating system 1108 stored in
the memory 1106, and interfaces with the user/other computers to
accept inputs and commands (e.g., analog or digital signals) and to
present results through an input/output (I/O) module 1110. The
computer program application 1112 accesses and manipulates data
stored in the memory 1106 of the computer 1102. The operating
system 1108 and the computer program 1112 are comprised of
instructions which, when read and executed by the computer 1102,
cause the computer 1102 to perform the operations herein described.
In one embodiment, instructions implementing the operating system
1108 and the computer program 1112 are tangibly embodied in the
memory 1106, thereby making one or more computer program products
or articles of manufacture capable of controlling AM process
parameters including, but not limited to, filament feed rate and
nozzle temperature, speed, and position, in accordance with the
design of the structures being fabricated. As such, the terms
"article of manufacture," "program storage device" and "computer
program product" as used herein are intended to encompass a
computer program accessible from any computer readable device or
media. In one or more examples, the computer program is implemented
in a numerical control programming language.
Those skilled in the art will recognize many modifications may be
made to this configuration without departing from the scope of the
present disclosure. For example, those skilled in the art will
recognize that any combination of the above components, or any
number of different components, peripherals, and other devices, may
be used.
CONCLUSION
This concludes the description of the preferred embodiments of the
present disclosure. The foregoing description of the preferred
embodiment has been presented for the purposes of illustration and
description. It is not intended to be exhaustive or to limit the
disclosure to the precise form disclosed. Many modifications and
variations are possible in light of the above teaching. It is
intended that the scope of rights be limited not by this detailed
description, but rather by the claims appended hereto.
* * * * *
References